MS Windows Longhorn is coming in 2005, and it will be using Mount Rainier--so we should see more and more drives supporting it. My guess is that Plextor, running an early version of Longhorn, discovered a problem. Since writing quality issues are more important, they disabled it for the time being to concentrate on the important stuff. Perhaps it will return in a later firmware. Of course, this is just a guess, but plausible.